“…The constructed coils were incorporated in an experimental low-field Halbach MR scanner that is currently under development at the Leiden University Medical Center (LUMC) [7]. The gradient coils were tested and used to acquire threedimensional images of different types of objects.…”
Section: Measurements Resultsmentioning
confidence: 99%
“…To address the difficulties that are encountered in a lowresource setting, new MR systems are being proposed such as MR scanners based on resistive magnets [5], [6] or systems that utilize a Halbach permanent magnet array [7], [8]. For a resistive magnet, gradient coil design runs along similar lines as for conventional MRI systems, albeit typically for smaller bore sizes and lower power requirements.…”
Section: Introductionmentioning
confidence: 99%
“…Furthermore, field simulations and measurements of these are presented, to show that the produced gradients are in good agreement with simulation, thereby verifying that the modified target field method can indeed be used to realize gradient coils in case the background field is transverse to the axis of the bore of a Halbach MR scanner. Finally, the gradient coils are incorporated in an experimental low-field Halbach MR scanner [7] thereby enabling us to use Fourier imaging techniques to acquire three-dimensional low-field MR images. Initial imaging results obtained with this scanner are presented as well.…”
In this paper we design and construct gradient coils for a Halbach permanent magnet array magnetic resonance (MR) scanner. The target field method, which is widely applied for the case of axial static magnetic fields, has been developed for a transverse static magnetic field as produced by a Halbach permanent magnet array. Using this method, current densities for three gradient directions are obtained and subsequently verified using a commercial magneto-static solver. Stream functions are used to turn the surface current densities into wire patterns for constructing the gradient coils. The measured fields are in good agreement with simulations and their prescribed target fields. Three dimensional images have been acquired using the constructed gradient coils with very low degree of geometric distortion.
“…The constructed coils were incorporated in an experimental low-field Halbach MR scanner that is currently under development at the Leiden University Medical Center (LUMC) [7]. The gradient coils were tested and used to acquire threedimensional images of different types of objects.…”
Section: Measurements Resultsmentioning
confidence: 99%
“…To address the difficulties that are encountered in a lowresource setting, new MR systems are being proposed such as MR scanners based on resistive magnets [5], [6] or systems that utilize a Halbach permanent magnet array [7], [8]. For a resistive magnet, gradient coil design runs along similar lines as for conventional MRI systems, albeit typically for smaller bore sizes and lower power requirements.…”
Section: Introductionmentioning
confidence: 99%
“…Furthermore, field simulations and measurements of these are presented, to show that the produced gradients are in good agreement with simulation, thereby verifying that the modified target field method can indeed be used to realize gradient coils in case the background field is transverse to the axis of the bore of a Halbach MR scanner. Finally, the gradient coils are incorporated in an experimental low-field Halbach MR scanner [7] thereby enabling us to use Fourier imaging techniques to acquire three-dimensional low-field MR images. Initial imaging results obtained with this scanner are presented as well.…”
In this paper we design and construct gradient coils for a Halbach permanent magnet array magnetic resonance (MR) scanner. The target field method, which is widely applied for the case of axial static magnetic fields, has been developed for a transverse static magnetic field as produced by a Halbach permanent magnet array. Using this method, current densities for three gradient directions are obtained and subsequently verified using a commercial magneto-static solver. Stream functions are used to turn the surface current densities into wire patterns for constructing the gradient coils. The measured fields are in good agreement with simulations and their prescribed target fields. Three dimensional images have been acquired using the constructed gradient coils with very low degree of geometric distortion.
“…The Image was acquired using a non-selective single-slice spin-echo sequence with the following parameters: Field of view: 128 × 128 mm, Acquisition matrix: 128 × 128, TR/TE: 500 ms/10 ms, scan duration: 2 min 4 s. In addition to this measured image, an MRI brain image obtained from [ 6 ] was used during the experiments. Further details on the low-field MRI scanners that are currently under development can be obtained from [ 2 , 15 , 16 ]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…The measured image that is used in this study was obtained from the low-field MRI system that is currently under development at Leiden University Medical Center (LUMC). Figure 2 shows this low-field MRI scanner [15] and a 2D phantom image [16]. The 3D-printed physical phantom displayed in Fig.…”
Background: Magnetic resonance imaging (MRI) is a safe non-invasive and nonionizing medical imaging modality that is used to visualize the structure of human anatomy. Conventional (high-field) MRI scanners are very expensive to purchase, operate and maintain, which limit their use in many developing countries. This study is part of a project that aims at addressing these challenges and is carried out by teams from
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